HOW TO MAKE PC BOARDS WITHOUT A LOT OF EQUIPMENT AND TIME: A Handy Shortcut Method That Actually Works.

 

Making your own PC boards is an essential capability when fabricating VHF RF circuits, such as the ones shown on this web site. After some research and experimentation, I have discovered a workable method that allows one to produce decent quality PC boards and skip the tedium involved in producing one-off prototypes, such as taping your entire artwork by hand, or even using photo etch resist methods, which are still time-consuming and require careful setup and fresh chemicals, not to mention some photo lab experience. The method about to be explained lets you produce circuit boards in about an hour, if you have an iron, a computer, drawing software and a laser printer.

The concept is based on the property of toner, little beads of plastic, encasing lamp black. Toner can be re-heated and offset onto other materials.

What You Will Need:

  1. Glossy, clay-coated paper.

  2. An iron (the kind the wife used to use back when there were things such as homemaking)

  3. A flat surface, such as the back of a large heat sink.

  4. Copper clad PC board, FR4 material or G10 epoxy.

  5. Etchant solution.

  6. Salt. (no, this is not for luck, it's a chemical enhancement for the etching process)

  7. Optional heat gun (to warm the etchant and speed the process)

  8. Drawing software on a PC with a laser printer (I use CorelDRAW, which works fine).

Design your artwork in the computer. Make it to exact scale. Observe spacing of leads on chips and capacitors and make measurements, rather than guessing. Most DIPs are 0.100" lead spacing, for instance.

Decide if the artwork is to be solder side or component side. Bear in mind that the artwork will "reverse" when ironed on to the PC board stock, so plan whether you need to flip the artwork in advance of printing.

Print your artwork on glossy coated stock. I have had decent results with Epson's Photo Quality Glossy Paper. Set your toner density to high, and make sure you have a cartrige capable of printing a dense, black image.

Place your PC board on the flat surface block, such as heatsink with double-sided adhesive tape. Place your artwork on top of it and fasten the paper in a few places with tape, onto the block so it doesn't slip while ironing.

I recommend that the PC board be 1/2" larger than the required artwork area. This is to reduce the possibility of edge lift-off when the paper is later removed.

With the artwork firmly in place, have a hot iron, set to the highest setting, and place the iron straight down on the paper. Press down, without moving it. Wait 10 seconds. Now, gently, with less downward pressure, slide the iron around to ensure even heating of the whole board/art. After about 2 minutes, you should have a good transfer. Be sure to iron down the edges extra carefully, as these can be prone to lifting accidentally.

Now take the PCB, art and block to a sink and pour full-strength dishwashing liquid on the artwork area. Let sit for 10 minutes. Paper should become translucent and art should be clearly visible. Paper may appear to be lifting in some areas as well. Now run cool water over the art paper for 1/2 hour, just a trickle. After 1/2 hour, turn the assembly sideways and let the water separate the paper from the copper. It should fall right off, leaving the toner traces, impregnated with clay on the PC board.

Inspect your board for any breaks in art, and for "bridges" between short-spaced clad patterns. Some clay may fill in these areas. It is a good idea to carefully scrape away these tight spots where bridges form. When you are satisfied that the art is clean, it is ready to etch.

Remove the board from the block, carefully, and place it in the etchant bath. Heat up the bath with a heat gun, so it is about 100-degrees F. Agitate the solution by rocking the container to make a wave washing across the board. It can stand for several minutes, but be sure to agitate for a couple of minutes every few minutes. Sprinkle some salt on the solution if the etchant is getting dark and the process seems to be slowing down. Salt activates the ferric chloride solution and is more economical than adding more ferric chloride to the bath. Board should be fully etched in about 30 minutes.

When you are satisfied with the completeness of the etching, remove it from the bath and rinse the board. The toner black will still be on the traces. This will need to be removed. Steel wool works well for this. Vigorous scrubbing will be necessary. Buff until all copper traces are shiny and free of toner.

Inspect your board and scrape away any "bridges" with an X-acto knife. You are now ready to drill. Using a precision drill press and a #64 drill, position your board carefully and drill each hole as indicated in your artwork (having the holes in the layout art will guide drilling nicely.

Remove any burrs and voila! A complete PC board, ready to stuff!

 

A great source of comprehensive information on making your own PC boards, right through to plated-thru holes, can be found at the link below.

Think & Tinker, Ltd.